Here's a step-by-step guide on dealing with a Type 1 slowly changing dimension (SCD) in SQL:

Introduction:
A Type 1 slowly changing dimension is used to update dimension attributes without preserving historical changes. When new data arrives, we simply overwrite the existing attribute values in the dimension table with the new values.

Step 1: Design your dimension table:

• Create a dimension table with columns such as the primary key (ID) and attributes.

Step 2: Update existing records:

• Identify the records in the dimension table that need to be updated based on the primary key.
• Use the UPDATE statement to set the attribute values to the new values from the source data.

Here's an example SQL script incorporating these steps:

-- Step 2: Update existing records
UPDATE dimension_table
SET attribute1 = new_data.attribute1,
    attribute2 = new_data.attribute2
FROM new_data
WHERE dimension_table.ID = new_data.ID;

In this script, dimension_table is the name of your dimension table, and new_data refers to the source data that contains the new values for the attributes. Adjust the table and column names according to your actual schema.

It's important to note that Type 1 SCD does not keep a history of changes. The existing attribute values in the dimension table are directly overwritten with the new values without preserving the previous values.

Remember to test the script thoroughly and adapt it to your specific database system and requirements.